Guaranteeing the traceability of each and every wafer in a manufacturing process of solar batteries realizes quality improvement, high homogenization, and production rate improvement. Furthermore, guaranteeing the traceability can bring extremely large effects such as quality assurance in the respective processes, handling of recalls in the market, and feasibility of feedback toward the production process.
In wafer management of the related art in a production process of solar batteries, wafers supplied by wafer makers are divided into arbitrary lots, and production is performed in each of the lots through a cell production process. In order to identify the lots, marks that identify wafers having a link with the lots are formed using an electrode formation paste from an Ag paste material or the like in an electrode formation process at the final phase of the cell process. Thereby, management of processes after the electrode formation process and wafer management at lot level are realized (for example, refer to PTLs 1 and 2). Furthermore, a technique in which recess portions and protrusion portions are formed on the surface of the wafer in a cell of a solar battery, and a specific character pattern is formed using the recess portions and the protrusion portions, thereby identifying the cell using the character pattern is known (refer to PTL 3).
In addition, in order to align the crystal orientation of a semiconductor crystal substrate with the locations of the alignment mark formed on the mask, a technique in which the semiconductor crystal substrate is etched so as to form a processing mark is known (refer to PTL 4). In addition, a technique in which a microwell having an inverted cone shape or other shape is formed in a silicon substrate so as to manufacture a microwell chip is proposed (refer to PTLs 5 and 6). Furthermore, a method of manufacturing a microprobe or a micro tip including a process in which recess portions are formed on a single crystal silicon substrate is known (refer to PTLs 7, 8, 9, and 10).
Furthermore, a method in which marks formed of dot holes are formed on a silicon substrate in order to perform marking on the silicon substrate is known (refer to PTL 11). In addition, a technique in which an inverted pyramid-shaped pattern is formed on a silicon substrate, and the pattern is used as a mark is known (refer to PTL 12).
That is, in the past, in processes after a module process in a production process of solar batteries, the lot of a cell was identified by reading the mark, and, similarly, a serial number was attached to a module. Thereby, a mechanism by which identification of which cell from which lot was used in which module was possible has been employed.